We propose to continue studies on porphyrins and on hemoproteins by x-ray photoelectron spectroscopy. In the past we have emphasized core-level studies on porphyrins and have learned something of the electronic structure of these compounds and also, that the iron core levels have a rather strong variation with oxidation state of the iron and with spin state. Henceforth we propose to emphasize hemoproteins in the expectation of applying the information we have on iron binding energies to draw conclusions about the hemoproteins. A great deal of this work will be concerned with discovering ways to maximize the signal from hemoprotein preparations, since they contain so little iron, and with devising methods to stabilize the various compounds of interest under the conditions of the photoelectron spectroscopic experiment.